[unreadable] Background and Significance. Diabetes is a growing, debilitating chronic disease that contributes to morbidity and mortality. Few studies have examined diabetes and comorbid conditions and their relationships to mortality over 9 years among adults aged 18 and over. [unreadable] Aims. For the population of adult enrollees with diabetes mellitus continuously enrolled in Group Health between 1997-2006, aims are to: 1) estimate the prevalence and incidence of diabetes and combinations of comorbid coronary artery disease (CAD), congestive heart failure (CHF), hypertension and depression in 1997-2006, describing temporal patterns separately for enrollees with prevalence diabetes in 1997 versus incidence diabetes in 1998-2006; 2) estimate the contribution of combinations of the four comorbid conditions to mortality in 1998-2006, relative to enrollees with diabetes alone; 3) among prevalence enrollees with diabetes in 1997 and alive through 2006, compare whether glycemic burden from treatment failure in 1998-2006 is lower in enrollees with diabetes alone than in enrollees with comorbid conditions; and 4) test for `reverse epidemiology' of cardiovascular risk by estimating whether greater HbA1c and cholesterol levels are related to lower mortality in 1998-2006 among enrollees with diabetes and CHF and/or CAD in 1997. [unreadable] Population. Group Health adult enrollees who are enrolled continuously from 1997-2006 and who had prevalent or incident type 1 or 2 diabetes during that time interval. Enrollees who died in 1997 are excluded, and enrollees who were alive or died in 1998-2006 are included. Eligible enrollees are divided into two mutually-exclusive cohorts: 1) prevalence diabetes (enrollees with diabetes in all years of the time series); and 2) incidence diabetes (enrollees with diabetes onset in 1998-2006). [unreadable] Study Design. A longitudinal cohort design will be used in all aims, with 1997 a baseline year in the 9-year (1998-2006) time series. [unreadable] Data Sources. Group Health automated data bases. [unreadable] Measures. Mortality, four comorbid conditions, Adjusted Diagnosis Group, diabetes complications, diabetes treatment type, personal and plan characteristics, smoking, obesity (BMI), blood pressure, HbA1c and cholesterol levels, utilization of providers and information, continuity of primary physician. Analyses. For Aim 1 descriptive statistics and time series graphs will be produced for the two cohorts describing the prevalence and onset of other four comorbid conditions. Measures will be constructed of the type and timing of comorbid conditions in the time series. In Aim 2 Cox proportional hazards regression models will estimate the association between the combinations of comorbid conditions and mortality. In Aim 3 multivariate regression models will estimate the relationship between combinations of comorbid conditions and glycemic burden. Aim 4 will test for reverse epidemiology using the Cox proportional hazards model. [unreadable] [unreadable] [unreadable] [unreadable]